The present invention relates in general to memory systems, and in particular to a memory system that provides for efficient use and allocation of memory resources in graphics applications.
Limited memory bandwidth has been a major obstacle in improving the performance of traditional 3-D graphics pipelines. Tiling or “chunking” has evolved as an alternative architecture that reduces the demand on memory bandwidth in 3-D graphics pipelines. A graphics pipeline using tiling architecture segments the rasterization area into a regular grid of tiles. Input geometry and commands are then “binned” into separate memory regions for each tile, such that only the geometry and commands which affect rasterization of a given tile need be read by the rasterization hardware. By storing, for example, one tile worth of data in memory that is local to the processor, external memory bandwidth requirements are significantly reduced.
While this type of tile-based architecture improves memory bandwidth, it also increases the demand for larger memory. Pipelining techniques whereby one frame is rendered at the same time the next frame is being binned, require even larger memory since a rendering buffer is provided in addition to a binning buffer. It therefore becomes necessary to allocate memory resources in this type of tiled architecture as efficiently as possible. Conventional approaches, however, pre-allocate a fixed amount of memory for each tile. In this type of memory system inefficiencies arise when, for example, the amount of geometry data for a given tile is larger than the pre-allocated amount of memory. This results in the inability of the graphics hardware to process all the data and render the tile. Conversely, a particular tile with a small amount of geometry data may require less memory than that provided by the pre-allocated memory resulting in portions of the pre-allocated memory to go unused.
There is therefore a need for a memory system that provides for more efficient use and allocation of memory resources in graphics applications.